The RSPCA and Mandurah Police are asking for members of the public to come forward with information following the incident.
A Mandurah dog owner has made the tough decision to put down an American Staffy cross after it was found with deep cuts on its torso and scratches to its face and paws.
RSPCA said Mandurah Rangers were called to collect the dog from Dudley Park last Thursday, where it was found to be mutilated.
The dog was found on Waterside Drive around one kilometre from its home.
Rangers rushed the animal to a local vet when the dog's owner was notified of the incident. The decision was made to end the animal's suffering and put it down.
The RSPCA said CCTV footage from the area shows the dog walking along Leslie St just 25 minutes before it was found wounded.
There are now calls for anyone with CCTV footage from the area around Leslie Street and Waterside Drive in Dudley Park from that afternoon, or if anyone noticed a pool of blood nearby, or if you've saw anyone suspicious in the area around that time to contact the RSPCA WA on 1300 278 3589 or WA Police on 1800 333 000.